Configuration File


Cayley expects, in the usual case, to be run with a configuration file, though it can also be run purely through configuration flags. The configuration file contains a JSON object with any of the documented parameters.

Cayley looks in the following locations for the configuration file

All command line flags take precedence over the configuration file.

Main Options


Determines the type of the underlying database. Options include:


Where does the database actually live? Dependent on the type of database. For each datastore:


The hostname or IP address for Cayley’s HTTP server to listen on. Defaults to all interfaces.


The port for Cayley’s HTTP server to listen on.


If true, disables the ability to write to the database using the HTTP API (will return a 400 for any write request). Useful for testing or instances that shouldn’t change.


The number of triples to buffer from a loaded file before writing a block of triples to the database. Larger numbers are good for larger loads.


See Per-Database Options, below.

Language Options


The value in seconds of the maximum length of time the Javascript runtime should run until cancelling the query and returning a 408 Timeout. A negative value means no limit.

Per-Database Options

The db_options object in the main configuration file contains any of these following options that change the behavior of the datastore.


No special options.



The size in MiB of the LevelDB write cache. Increasing this number allows for more/faster writes before syncing to disk. Default is 20, for large loads, a recommended value is 200+.


The size in MiB of the LevelDB block cache. Increasing this number uses more memory to maintain a bigger cache of triple blocks for better performance.



The name of the database within MongoDB to connect to. Manages its own collections and indicies therein.